This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this study is to evaluate the safety and effectiveness of islet cell transplantation alone in patients diagnosed with difficult to control Type 1 diabetes mellitus without kidney failure. Difficult to control Type 1 diabetes is defined as wide swings in blood glucose that disrupt the patient's life and result in frequent episodes of low blood glucose despite the proper use of standard insulin therapy and frequent blood glucose monitoring. Type 1 diabetes is associated with the damage of a specific cell subtype of pancreatic islets, which makes patients depend on an outside source of insulin. Despite insulin treatment, there is a significant risk of long-term problems, including damage to the heart, blood vessels, nerves, eyes and kidneys. The results of recent research studies suggest that these complications are caused by poor glucose control. Transplantation of islets offers the prospect of good glycemic control without the major surgical risks associated with whole pancreas transplant and may result in independence from insulin injections. Recently, a group of investigators in Edmonton, Canada used a combination of anti-rejection drugs to help prevent the rejection of transplanted islets and showed that the regimen was effective in more than 75% of the cases who were followed up to 20 months. This study is being performed to confirm the results of the Edmonton study to see if islet transplantation alone is a safe and effective way of treating patients with type 1 diabetes.